In Oil and Gas industry, offshore and onshore drilling are identified as focus areas. With new discoveries through shale gas and new technology in directional drilling, there is steep increase in demand for drilling equipment, particularly in the safety- and application-critical equipment. To meet this growth in demand of safety and application critical components productivity improvement and innovation in manufacturing process is essential.
Many industries including oil and gas industries use safety and application critical components. For many decades many of these components have been manufactured using conventional manufacturing process (i.e., open die forging followed by machining). In these methods an ingot is cogged into bloom, which is followed by saw cutting, rough sizing, rough machining, heat treatment, semi finish machining and finish machining of the component.
In a nutshell, the existing manufacturing method is the combination of “Open die forging, machining and heat treatment”. In this process, 10 to 15% of shape formation is achieved through open die forging and remaining 85 to 90% shape is achieved through machining. The existing process results into about 40% utilization of material thereby leading to about 60% wastage of material from cogged bloom to finished part. It is to be noted that the said cogged blooms are formed through open die forging and which are in rough shape and sized to rectangular blank for machining.
During mass production of such components, substantial raw material is wasted with conventional manufacturing method which results into large machining time and poor yield. It is important to have near-net shape input to machining in order to establish right balance between forging and machining process to effectively utilize material and machining time which leads into improved productivity of such parts without compromising on the desired mechanical properties and specific strength.
The review of the existing forging methods reveals following technology gaps such as lack of right combination of design and manufacturing process at the forging stage of manufacturing the part. For example, the U.S. Pat. No. 6,032,507 states ‘The forging of small, complex shaped metal parts is problematic. Such parts can be produced by hot forging processes. However, these processes are not completely satisfactory for various reasons, including that hot forging processes result in significant flash (excess material) being formed on parts. This flash must be removed by a machining operation such as grinding, which increases the cost and difficulty of producing the finished parts. Furthermore, hot forging processes inefficiently utilize workpiece material because the flash is waste material. Accordingly, it is desirable to produce such parts by a forging process other than hot forging.’ U.S. Pat. No. 6,032,507 provides female dies of closed die sets, and methods of near net warm forging parts utilizing the female dies, that can be used to manufacture parts when the workpieces do not fit in the die cavities of the female dies. These female dies can be used in conventional closed die sets in combination with conventional forging presses to near net warm forge parts.
However, hot forging processes are economical and still widely known. There is therefore a need to provide a hot forging manufacturing process wherein the forging is modified to near-net shape so as to enhance material utilisation, thereby improving the yield and reducing material wastage without compromising on final part specification.